Long-Term Quantitative Evaluation of Muscle and Bone Wasting Induced by Botulinum Toxin in Mice Using Microcomputed Tomography

Abstract

Muscle and bone masses are highly correlated and muscles impose large loads on bone. Muscle wasting that accompanies bone loss has been poorly investigated. 21 female mice were spread into seven groups. At day 0, 18 mice received Botulinum toxin (BTX) injection in the quadriceps muscle to induce paralysis of the right hind limb; the left contralateral side was used as control. Mice were sacrificed at 7, 14, 21, 28, 56 and 90 days post-injection. A remaining group was sacrificed at day 0. Trabecular bone volume was determined by microcomputed tomography (microCT) at the distal femur and tibia proximal metaphyses on both sides. Limbs were immersed in an HgCl solution allowing muscle visualization by microCT. On 2D sections, the cross-sectional areas and form-factors were measured for the quadriceps at mid-thigh and gastrocnemius at mid-leg and these muscles were dissected and weighed. Bone volume decreased in the paralysed side. Bone loss was maximal at 56 days followed by recuperation at 90 days. The cross-sectional areas of gastrocnemius and quadriceps were significantly lower in the paralysed limb from 7 days; the decrease was maximum at 21 days for the gastrocnemius and 28 days for the quadriceps. No difference in form-factors was found between the two limbs. Similar results were obtained with the anatomical method and significant correlations were obtained between the two methods. Quantitative analysis of muscle loss and recovery was possible by microCT after using a metallic contrast agent. Loss of bone secondary to muscle wastage induced by BTX and recovery showed a parallel evolution for bone and muscles.

Mandibular bone effects of botulinum toxin injections in masticatory muscles in adult

“…There are few articles in the literature on the natural history of condylar bone changes in patients with TMJD. Significant condylar bone changes are found in 68% of cases at the TMJ after radiological follow-up during 13.4 months [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] in patients presenting TMJD 46 .…”

“…It leads to a transient muscle paralysis by a "functional denervation" 2 . In laboratory animals, a single BTX injection in the quadriceps induces a disuse bone loss at the tibia and femur with a considerable muscle wasting 3,4 . In humans, the effect of BTX disappears after two to four months and muscle strength starts to reappear three to four months later 5 .…”

Masseter muscle atrophy impairs bone quality of the mandibular condyle but not the alveolar process early after induction

“…Also, repetitive interventions demonstrated bone loss in the mandibular angle in a clinical trial . The lower limbs of female mice also experienced bone loss, but the long‐term evaluation showed muscle recovery at 56 days whereas femur deterioration was reversed after 90 days . However, the recovery might be comparatively slower in the masticatory apparatus, as demonstrated by a study in adult female rabbits, where the muscle still exhibited signs of atrophy and the condyle still showed a reduced bone quality 12 weeks after injecting BoNTA in the masseter muscle …”

“…43 The lower limbs of female mice also experienced bone loss, 46,47 but the long-term evaluation showed muscle recovery at 56 days whereas femur deterioration was reversed after 90 days. 47 However, the recovery might be comparatively slower in the masticatory apparatus, as demonstrated by a study in adult female rabbits, where the muscle still exhibited signs of atrophy and the condyle still showed a reduced bone quality 12 weeks after injecting BoNTA in the masseter muscle. 19 The mandibular condyle and the alveolar process are influenced differently by masticatory loading due to particular structural and anatomical features.…”

Herbst appliance anchored with miniscrews: Some unsettled questions

“…In the rat, we recently confirmed the vanishing effect of BTX and its effects both on muscle and on long bones. 4 Fourth, the authors indicate that there are only a few clinical studies on the effects of BTX treatment on bone. A recent study from our group identified alveolar and condylar bone changes in adult patients at the mandible after BTX injections into masticatory muscles.…”